Automatic self closing stair



March 19, 1935.

H. CHAMBERS AUTOMATIC SELF CLOSING STAIR Filed Sept. 4, 1931 4 Sheets-Shet 1 I N VEN TOR. Horn/79mm Chambers A TTORNE Y.

March 19, 1935. H. CHAMBERS I AUTOMATIC SELF CLOSING STAIR 4 Sheets-Sheet 2 Filed Sept. 4, 19:51

[XI 'ENTOR. ambers lllll March 19, 1935. H. CHAMBERS 1,994,883

AUTOMATIC SELF CLOSING STAIR Filed Sept. 1931 4 Sheets-Sheet 5 INVENTOR. Harm/791270 Chambers A TTORNE Y.

H. CHAMBERS 1,994,883

AUTOMATIC SELF CLOSING STAIR March 19, 1935.

4 Sheets-Sheet 4 Filed Sept. 4, 1951 I N V EN TOR. Harr/ngfan Chambers Patented Mar. 19, 1935 UNlTED STATE S PATENT orrlea '7 1,994,883 AUTOMATIC SELF CLOSING STAIR Harrington Chambers, Flushing, N. Y; Application September 4,1931, Serial No. 561,097

9 Claims. (01. 228-50) 4 This invention relates to stair constructions and is directed more particularly to improvements on the stair installation described and claimed in my Patent, No. 1,815,048, dated July 21, 1931'. In that patent, the stair construction disclosed is adapted to be associated with a well in an upper floor and is adapted to be let down into a position to provide communication between the floors and to be shifted upwardly to lie wholly above the upper floor and to be concealed when in this latter position by a trap door in the well opening. In said construction, the stair is counterbalanced to facilitate its manual manipulation and the counterbalancing means is such that the stair will be maintained by gravity in its lowered operative position and has to be raised by manual force into its inactive or concealed position.

In contradistinction to my prior construction, the stair of the present invention is so constituted that it is automatically self closing, and when lowered into its operative position serves to ener-' gize means which tends to return it to its raised position. Means is, however, provided which serves to lock the stair in its loweredposition until manually released whereupon the stair will be automatically raised and moved into concealed position, there being mechanism" provided to check its movement into final position and; to thereby preclude shock due to its automatic operation.

Aside from the broad automatic self closing feature to which I have referred, the invention embodies numerous other features which will be M hereinafter more fully explained, and set forth wholly automatic manner when the locking means associated therewith is manually released.

A further important feature of the present invention is inherent in certain adjusting devices which permit of accurate regulation of the tension of the springs associated with the stair in such manner as to insure smooth and efiicient operation.

Features of the invention, other than those specified, will be apparent from the hereinafter detailed description and claims when read in conjunction with the accompanying drawings.

The accompanying drawings illustrate one practical embodiment of the invention, but the construction therein shown is to be understood s illustrative, only, and not as defining the limits of the invention.

Figure 1 is a side elevation of stair construction embodying the present invention, certain parts being shown insection in the interest of clearness. In this view, the" stair is shown. as lowered to permit access between upperandlower floors.

Figure 2 is a view similar to Figure 1, but showing the stair in raised, concealed position.

Figure 3 isan enlarged fragmcntal detail of the structure as shown in'Figure 2,'showing-the attachment of the stairto the trap door. Figure is a section on the line 4-4 of Figure 3. Figure 5 is a section on the line 55 of Figure 2. "Figure 6 is a vertical section through the upper end of the stair showing the stair partially raised. Figure 7 is a section through the stair well of the upper floor showing the anchorages for the tension means and associated sheaves situated atthispoint- V Figure 8 is a section on the line 8-8 of Figure '7. Figure 9 is aplanview of one'of the adjusting devicesshown in Figure '7. V I

Referring to the drawings, 1 designates an upper floor and 2 a lower floor between which communication is desired by the stair of this invention. The upper floor is provided with a stair well opening having a suitable jamb 3.

The well opening is adapted to be closed from below by a trap door 4 hinged to the jamb- 3 by means of hinges 5. The trapdoor 4 has spaced from its lateral edges longitudinally extending stifieners 6 and is adapted to be" moved on the hinges 5- from a position where it closes "thewell opening, downwardly into 'a' position to-open said opening. Extending across the jamb' 3 of the well opening above the door 4 is a shaft 7, theoriposite ends of which are permanently secured by brackets 8, which are screwed to the jamb as in- On this shaft are mounted two dicated at 9. rollers 10 and with these rollers are adapted'to cooperate the stringers of the stair. These stringers are indicated at 11. There are two of them and they are spaced apart by treads 12, which extend between them. Risers may be provided if desired, but ordinarily they are preferably omitted. I 1 r Y The stair may have a bannister orrailing 13 supported by posts 14 rigidly securedto the stringers. The stringers 11 areadapted to rest upon the two rollers 10, rubber tired, if desired, as indicated in Figure 6 and with each ofthese rollers is associated a bracket 15 having inner and outer flanges 16 and 17, which overlap the lower edges of the stringers as shown in 'Figures 5 and 6, so that the flanges '16'are adjacent to and may engage the inner face of the stringers, while the flanges 17 engage the outer face, and these flanges thus serve to preclude lateral movementof the stringers WithIGSDBCt to the rollers 10 and insure that the string'ersride upon these rollers at all times. I 7

One ofthe brackets 15 and the corresponding roller 10 is precluded' from longitudinal movement on the shaft 7 by cotter pins 18, as shown in Figure 5, although the other roller with its bracket may be free to move longitudinally of the shaft to compensate for slight variations in width of the stair. The flange 17 of each of these'brackets is, however, provided with an elongated follower 19 adapted to extend into a slot 20 formed on the outer face of each stringer and through the cooperation of these parts the stringer is precluded from lifting off of the associated roller 10. The followers 19 are elongated as shown, soas to preclude binding during the operation of the stair.

The main portion of the weight'of the stair is carried by the shaft 7 through the rollers 10, but the stair is also operatively connected to the trap door :4, so that thetrap door and the stair will pivotallymove together. To this end, the trap door is provided near its free end with a shaft 21 extending transverselybetweenthestiifeners 6 and secured thereto by fixtures 22. On this shaft 21 are-mounted brackets. Each bracket comprises two plates 23 and 24, the former of which is on the inside of the stringer and the latter of which is on the outside of the stringer, and these two plates-overlapthe lower margin of the stringer, as shown in. Figs. 3 and 4; Between each of the plates 23 and 24, are pivoted two rollers 25 onwhich the lower'edge of the corresponding stringer rides, and the plate 24 carries an elongated follower 26'which works in the guide-slot 20 of the'stringer. A corresponding arrangement is provided for each stringer.

'Bythis arrangement, the stringers areadapted to ride on the rollers 25, and although the plates 23 and 24 are pivotal with respect to the-shaft-21, the double-rollers 25 and the elongated follower 26 preclude I cramping due to different" angular relations betweenthestair-and thetrap door and thus provide fora smooth, silent andwfreerunning operation. The part 27-shown in Figure 3 is amember of resilient material, one of which is mounted adjacent thelower end of each stringer, so that as the stair. is slid in an upward direction, these bumpers will engage with theplates 24 and form stops to such. upward movement with-. out appreciable shock or jar.

By virtue of the mounting of the stair onthe rollers "10 of the shaft 7 and therollers 25 of :the shaft'21, the stair is 'mo-unted for substantially anti-friction longitudinal movement whereby; it is adapted to be moved upwardlyand then pivotallyinto the position of Figure 2 and returned from this position into a position of:Figure-;1. In order that the movement of the stair may be properly counterbalanced. and efiectually controlled, there isassociated with the sair appropriate counterbalancing and operating means next to be described. Mounted at the sides of the well on the-jamb 3 andat the end thereof distant from the shaft '7, are two brackets 28, oneof= which is positioned at each side of the well and is firmly screwed thereto in a rigid manner. Each of these brackets carries a sheave 29, which is lined-up with asheave 30 on the shaft 7, there bein pa; sheave 30 adjacent each end of this shaft. Two

long helical springs 31 areanchoredrto fittings 32 adjacenteach lateral edge of the'trap door 4 and nearits-free end. These springs extend upwardlyover the sheaves 29, thence to and about i the sheaves 30 andthence forwardly in the direc-- tion of the brackets 28.where their ends are anchored. The ends of these springs are-notdirectly anchored to the brackets 28, butare securedthcreto through intermediate regulating means shown in detail in Figures 7, 8-and 9. In

these figures, each bracket 28 is shown as having a stud 32 which extends outwardly to a. point in line with the sheave 29. To the outer end of this stud is pivotally secured a link 33 having therein a series'of perforations 34. The link is adapted to extend into the interior of the associated spring 31 and the adjacent end of the spring is coiled to provide a fastening means for a loop member 3-5 through the perforated ends of which a bolt 36 is adapted to be passed and bolt-may be associated with any one of the perforations 34 as may be found necessary to impart the desired tension to the spring.

Both of the springs 31 are connected to their corresponding brackets 28 in the manner described. The upper ends of thebrackets 28 are connected by a rod 37 and to this rod is connected two links 38, which are identical with the links 33, except that their ends are twisted and are lined up with sheaves 39' on the shaft 7. To the links 38, springs 40 are adjustably secured in the same manner as the springs 31 are secured to the studs 32'. These springs extend from the links 38 about the sheaves 39 and thence longitudinally along the sides of the stringers to a point adjacent the lower end of the stringers where they are anchored to braokets4l.

It will be noted from Figure 5 that the cotter pins 42 serve to preclude shifting of the sheaves 30 and 39 longitudinally of the shaft/7, this arrangement being duplicated at both ends of the shaft.

It will be noted from the description of the parts as thus far advanced that the springs 31 serve to counterbalance the weight of the door andstair in a substantially vertical direction, While the springs 40 serve to counterbalance the weight of the stair in a longitudinal direction. In accordance with the present invention, the stair will tend normally to longitudinally elevate unless locked in lowered position.

In order to precludeinadvertent closing of the stair, I provide locking meansnext to be described. The .top step or tread 43,- as shown in Figure 6, extends across the upper ends of the stringers which are cut on a miter, so that the tread. 43 will be horizontal when the stairs are lowered. This tread is supported on the stringers by means of fittings 44 which are preferably stamped up from sheet metal'and are so formed as to serve as either rights or lefts. Each of these fittings is provided therein with two recesses 45 which are lined up with pins, one of which is lined up with apin 46 mounted on one of the brackets 15. Adjacent the recess 45 which is lined up with the pin 46 is a pivot 47 to which is pivotally secured a latch 43, the lower end of which is curved to form a cam face 49, terminating in a cutout 50, complementary to the recess 45. The latch 48 normally gravitates into a position to close the outlet of the recess 45, with the cam face 49 line up with the pin 46.

When the stair is lowered, it slides longitudinally of the bracket 15 'until it reaches its lowermost position, whereupon the cam face 49 will engage with the pin 46 to cause the latch to be swung upwardly into the dotted line position of Figure 6 to permit the pin to enter the recess 45 upon the advent of which the latch will fall into the full line position, thereby locking the pin in the recess. 1 By this arrangement, the stair is locked in lower position and although the tendency of the springs is to lift the stairs, this cannot occur until the latch is released. The release of the latch is accomplished by means of a trip lever 51 having a slot 51, pivoted at 52 on the fitting 44 and having associated therewith a pull cord or chain 53 which, when manuallyoperated, will .lift the latch into the dotted line position of Figure 6, and-leave the stair free for operation bythe springs as stated. -A spring "49a assists gravity in maintaining the latch in looking position. Slot 51 precludes the lever 51 and the latch 49 from binding during operation.

During the operation of the stair, my experience has shown that there is a tendency of the springs 40 to-strike against the stiffeners 6 and produce noise. This is obviatedxby providing two or three felt or. rubber silencing strips 54 on the outer face of each stiffener 6.

Practical experience with thestructure of the character. described has fully demonstrated its efficiency. The parts may be so adjusted that very little manual effort isrequired to lower the stair, this. being accomplished by a downward pull on a pull chain 55 secured to the trap door as shown in Figure l. The pullchain is pulled downwardly until the stair is within convenient reach whereupon the stair is grasped and easily drawn downward until, it .reaches its lowermost position whereupon the ,latch 48 automatically locks it in place. The parts remain in this position until it iszdesired to raise the stainwhereupon the pull cord 53 which is of convenient access is pulled to release the latch and the stair thereupon is automatically elevated by-the springs. In order to provide for relatively quick closing without jar or shock when this operation is comsired to close the'same and for the first time provides a self closing stair of the character un-- der consideration. When the stair is down, the weight of thestair and 'doorwill overbalance the tension of the springs '31, so that the' stair will rest firmly on the floor and will not tend to shift. The tension of springs 40, however, is such that they overbalance the weight of the stair in a-longitudinal direction and tend to lift the same, butlatch 48 looks the stair against this movement. When the latch is released the stair is immediately and automatically moved upwardly in a longitudinal direction by the springs 40. As the stair is raised, the weight of the stair imposed upon the door is progressively diminished to permit the springs 31 to come into operation to overbalance the weight of the door and stair ina vertical direction with the result that the stair is pivoted into substantially horizontal position and the door is closed.

I In practice these operations occur progressively and the tensions of theseveral'springs coact in such manner that duringthe shifting of the center of weight of the stair, the springs 31 smoothly enter into the operation and thereafter cooperate with spring 40 to move the parts into final position noiselessly and without shock, jar or vibration.

The'foregoing detailed description and the accompanying drawings show the invention in its preferred, practical form. I am aware, however,

that the invention is capable of modification without departing from the'spirit'or scope of the appended claims which are to be construed in this light.

In' practice, I find it cross rod 37 somewhat lower than shown in the drawings and'sufficiently closeto the sheaves 29 to retain the springs 31 in said sheaves, sothat they cannot be inadvertently displacedorshift off the sheaves. Similarly, the sheaves 30 and 39 are placed suificiently close to the jamb 3, as shown in Figure l, and the springs 31 and 10 are retained by said jamb in said sheaves.

Having thus fully described the invention, what I claim as new and desire to, secure by Letters Patent is:

1. In a stair construction adapted to be used be.- tween lower and upper floors, the latter of which desirable to mountthe adapted-when in horizontal position to close the opening and which door is hinged to be opened into a downwardly inclined position, a shaft rigidly mounted to extend across the well opening near one end thereof, spaced apart rollers on said shaft, brackets associatedwith said rollers, similarly spaced rollers and associatedbrackets near the free end of the door, a rigid stair mounted to rest on said rollers and engage withthe corresponding brackets and torslide longitudinally thereon andto move pivotally when the door is pivotally moved, one of the rollers and the corresponding bracket on said shaft being fixed against movement longitudinally of the shaftand the other roller and the corresponding'bracket being adapted for longitudinal adjustment on the shaft to compensate for variations'in stair width, lifting means tending to 'impelthe. stair in a longitudinal upward direction, lifting means tending to close thedoor as the stair is elevated, locking means for locking the .stair ina lowered position with the door opened,zand means for releasing the locking means to permit the lifting,

means to elevate the stair and closethe door.-

2. In a stair construction adapted to be'used between .lower and upper floors, the latter of which is provided with a stairwell opening, a trap door adapted when in horizontal position to close the opening and which door is hinged to be opened into a downwardly inclined position, a shaft rigidly mounted toextend across the well opening near one end thereof, spaced-spart rollers on said shaft, pivoted brackets mounted adjacent the free end ofthe door and similarly spaced, a plurality of rollers on 'each of said brackets, a rigid stair having treads and. stringers with the stringers positioned to rest upon and longitudinally travel on the rollers of the shaft opening near oneendthereof, spaced apart rolland brackets, the stringers being provided on their outer faces with guides, an elongated follower'carried by each of said brackets and. cooperating with the. guides to hold. the stringer in contact with the rollers of said brackets, the rollers of the door brackets being spaced the stair is elevated, additional 'springstensioned to elevate the stair through the well.opening,iso that the door can be closed, and means for lock-, ing the stair in lowered position with the door open; said means being :releasable to allow the springs to elevate the-stair andclose the door;-

3. Inastairconstruction adapted to. be used between lower and upper floors, the latter of which is' provided with a stair well having a hinged .trap door therein, a'rigid stair mounted forsliding movement longitudinally of the door, springs anchoredto thestair and t the door and also anchored with respect to the upper floor, the anchorages of the springs to the upper floor comprising adjustable links, whereby the tensionof the springs may be regulated, and directional sheaves coactingwith the springs to impress the tension of thespringson' tothe door and stair, so as-to cause thestair toibe elevated and the door to be closed when the stair is elevated, means for locking the stair in lowered position with the 'door open, and means forireleasing thelocking means to permit the springs to lift'the-stairvand close the door.

4. In a'stair construction. adapted to beused between lower and. upper floors; the latter of which isprovided with a stairwell opening having ahinged trap door therein, guiderollers mounted inear thezfreeaend; of the door, a shaft extendingisuninterruptedlyr across the well. openingxat-the end thereof at which the door is hinged and which shaftis supported. at its opposite ends onlthexjamb' on opposite sides of said well opening,- rollers carriedl'by'saidxshaft, a rigid' stair embody-ingstringers and treads mounted with the lower edges of; the: stringers bearing upon the rollers on the door andushaft to mount said stair for longitudinal movement, helical coil springs securedito thestairiandjamb for counterbalancing.:the;weight ofthe stair in the direction of its length, r and zhelical coil springs, separate from andsindependent'bfthesaid coilsprings of the stair and jamb, secured to the jamb and doorfor counterbalancing the weight of the door and stair ima substantiallyfvertical direction, whereby the stairiisscounterbalanced in the direction of its length independentlytof .its counterbalancing in asubstantially vertical direction, meansfor tensioning saidfsprings to providetherein sufficient tension ito'elevate the stair and thereupon close the doom-and imeanszforlocking: the stairlin lowered'position with the door openagainst-the tension iofisaidisprings, said last mentioned means b'eingr'releasable:toi'permit the stair to be lifted andrthe'doornlosediby said springs.

'5; An adjustable connector for securing one end of a coil spring to an anchorage including a coil spring; said connector'comprising a'rod having atone end an attaching member and provided with perforations spaced longitudinallythereof, a loop member adapted to engage with the coil of the'spring, and a bolt passing through said loop member and'adapteditobe passed through any oneof said perforations.

'61 In a'stair construction; adapted to be used between lower and ,upper floors, the latter of which is provided with a stair well opening, a

trap door adapted when in horizontal position towclosethe opening and which door is hinged to be openedinto a downwardly inclinediposition, a rigidstair embodyinglst-ringers and treads, means for mounting the stair for longitudinal 1 movement in the direction of its length through the well opening and for pivotal movement with the door; helical springs for counterbalancing the weight ofthe stairinthe direction'of its length and the weightof the door and stair in a substantially vertical direction, said springs being sufficiently strong'to normally tend to elevate the stair in the direction of its length and thereupon pivotally close-the door, locking means for'lockingthe stair against upward movementin the direction of its length under the tension of the springs, manually operable means for releasing said'locking meansto permit the stair to be e1evated, whereby, with an. accompanying upward movement of the center of weight "ofthe stair, the door may be closed under the tension of the springs, and means for checking the closing movement of the door and. concurrent pivotal movement of the stair to preclude slamming of the door when the stair is in fully elevated position.

'7. A stair construction adapted to be used between lower and upper floors, the latter of which is provided with a stair well opening having a hinged trap door therein, a rigid stair slidably secured to the door for movement in the direction of its length and embodying stringers and treads, lifting means for normally impelling the stair upwardly in the direction of its length and for thereupon pivotally impelling the door into closed position, means for locking the stairagainst upwardmovement in the direction of ,7 its length under the power of the lifting means, means for releasing said locking m'eans to permit the stair to move upwardly in' the direction of its length with an accompanying upward movement of the center of weight of the stair, and means for slow- 1y dissipating the upward momentum of the stair and door as they approach the upward termini of their respective travels to cushionably bring them to a state of rest with the doorin closed position. l

8; A stair construction adapted to be used between lower and upper floors, the latter of which is provided with a stair well opening having a hinged trap door therein, a rigid stair slidably secured to the'door for movement in the direction of its length and embodying stringers and treads, lifting means for normally impelling the stair upwardly in the direction of its length andrfor thereupon pivotally impelling the door into closed positionfand means for slowly dissipating the upward momentum of the stair and door as they approach the upward termini of their respective travels to cushionably bring them to a state of rest with the door in closed position.

'9. In a stair construction adapted to be used between lower and upper floors, the latter of which is provided with'a stair wellopening having a trap door, a rigid stair mounted for longitudinal sliding movement upwardly and downwardly in the direction of its length through the well opening and for pivotal movement during such sliding movement, lifting means of sufficient strength to normally lift the stair into a position above the ceiling of the lower floor and close the door, means to lock the stair in loweredposition against the power of the lifting means, after the stair has been lowered, manually operable means to release said locking meansand thereby render the stair responsive to the power of the lifting means, whereby said stair will be automatically lifted to a position above the ceiling of the lower floor and the door closed, and means for slowly dissipating the upward momentum of the stair and door as they approach the upper terminal of their respective travels to cushionably bring the stair and door to a state of'rest-without shock or jar. a

. HARRINGTON CHAMBERS. 

